Floods and Hydrological Vocabulary

This set covers essential terminology, forecasting metrics, and typical effects related to floods as described in the lecture notes.

Floods

Inundations of land with water caused by rains, rivers overflowing their banks, increase in reservoirs of water, winds, cyclones, tsunami, melting of glaciers and sea tides.

Flash flood

A violent splash of water caused by a river breach, a dam burst, a thunderstorm, or a tsunami.

Drainage basin

The area drained by the waters of the river.

Flood plain

The flattish area alongside river channels covered by water during floods.

Catchment area

The area in the upper course of the river which catches rainfall and feeds the river.

Tributary

A stream or a smaller river joining the main river.

Origin

The point from where a river begins its course.

Mouth

A point or place where the river joins the sea.

Water divide

The high relief feature that separates two drainage basins.

Run off

The surface flow of water.

Probability period

The period prior to the onset of a flood, characterized by persistence or intensity of rain and heavy runoff, during which the likelihood of flooding becomes apparent.

Central Water Commission (CWC)

An organization that has about $132$ forecasting stations in the country and issues over $6000$ forecasts annually.

Lag-time

The interval between heavy rainfall and flooding (peak discharge).

Peneplain

Low lying areas of the flood plain located at the mouth of a river or stream.

Typical Effects of Floods

Consequences including panic, spread of diseases (epidemics, viral infections, malaria, and diarrhoea), physical damage to crops and structures, and soil erosion.